Make-Up Air Heat Recovery Using Exhaust Air in PTAC Units
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Solution Overview
Problem
Packaged terminal air conditioner units (PTACs) face inefficiencies due to the introduction of outdoor make-up air, which adds a significant heat load to the conditioned space, leading to excessive energy losses.
Innovation Solution
Incorporation of a heat transfer assembly, including a heat pipe, between the intake and exhaust apertures to transfer thermal energy between make-up and exhaust air flows, enhancing energy efficiency by minimizing heat exchange losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If outdoor make-up air is introduced into the indoor portion, then the air quality and pressure balance are improved, but the heat load and energy consumption increase significantly
Solution Approach 1:
The system performs preliminary heating of the outdoor make-up air using exhaust air heat transfer before it enters the indoor portion. The heat transfer assembly pre-conditions the make-up air by transferring thermal energy from the exhaust air stream, reducing the subsequent heating load required by the main heating system.
Solution Approach 2:
The system converts the wasted thermal energy in the exhaust air stream into a useful resource for pre-heating the incoming make-up air. Instead of discarding the heat from exhaust air, it is captured and transferred to the colder make-up air, turning a harmful energy loss into a beneficial pre-conditioning mechanism.
2Loss of energy
If a heat transfer assembly is added to recover thermal energy, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The heat transfer assembly acts as an intermediary component between the exhaust air stream and the make-up air stream. It facilitates thermal energy transfer from the warmer exhaust air to the cooler make-up air without requiring direct mixing of the two air streams, enabling efficient heat recovery while maintaining air quality separation.
Solution Approach 2:
The heat transfer assembly serves multiple functions: it recovers thermal energy from exhaust air, pre-heats incoming make-up air, reduces the load on the main heating system, and improves overall system energy efficiency. This multi-functionality justifies the added complexity by delivering multiple benefits from a single component addition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The heat transfer assembly effectively reduces energy losses by utilizing the thermal energy of exhaust air to condition make-up air, improving the overall efficiency of the PTAC unit.
Implementation Method 1
a heat pipe that extends from the intake aperture to the exhaust aperture for transferring thermal energy between the flow of make-up air and the flow of exhaust air
Data Source
AI summary
An air conditioner unit includes a bulkhead defining an indoor portion and an outdoor portion, an intake aperture and an exhaust aperture defined in the bulkhead, an intake fan fluidly coupled to the intake aperture for urging a flow of make-up air through the intake aperture into the indoor portion and an exhaust fan fluidly coupled to the exhaust aperture for urging a flow of exhaust air through the exhaust aperture into the outdoor portion, and a heat transfer assembly extending between the intake aperture and the exhaust aperture for transferring thermal energy between the flow of make-up air and the flow of exhaust air.